Though he had a normal childhood on Earth, Aoi learns he's the successor to alien Queen Mito, whose people choose their own sex. Complicating matters is Aoi's love for Mutsuki, a policewoman tracking Mito. When Aoi unexpectedly turns into a beautiful woman -- the new queen -- he/she joins forces with Mutsuki to bring down a potent enemy capable of obliterating entire planets. Meanwhile, the two must find a way to redefine their relationship.